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Stabilizing triplet excited states for ultralong organic phosphorescence

Nature Materials volume 14, pages 685–690 (2015)Cite this article

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Abstract

The control of the emission properties of synthetic organic molecules through molecular design has led to the development of high-performance optoelectronic devices with tunable emission colours, high quantum efficiencies and efficient energy/charge transfer processes1,2,3,4. However, the task of generating excited states with long lifetimes has been met with limited success, owing to the ultrafast deactivation of the highly active excited states5. Here, we present a design rule that can be used to tune the emission lifetime of a wide range of luminescent organic molecules, based on effective stabilization of triplet excited states through strong coupling in H-aggregated molecules. Our experimental data revealed that luminescence lifetimes up to 1.35 s, which are several orders of magnitude longer than those of conventional organic fluorophores6,7, can be realized under ambient conditions. These results outline a fundamental principle to design organic molecules with extended lifetimes of excited states, providing a major step forward in expanding the scope of organic phosphorescence applications.

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Figure 1: Schematic representation of the manipulation of the lifetime of excited states in inorganic and organic materials.
Figure 2: Investigation of the photoluminescence of a nitrogen-based model molecule (DPhCzT) under ambient conditions.
Figure 3: Proposed mechanism for ultralong phosphorescence of the DPhCzT aggregates.
Figure 4: Versatile molecular design for ultralong phosphorescence with tunable colours and data encryption application under ambient conditions.

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Acknowledgements

We thank Y. Wang, W. Zeng, T. Tsuboi, C. Zhang and G. Xing for technical assistance. This study was supported by the National Natural Science Foundation of China (grant No. 21274065, 21304049, 61136003 and 51173081), the Ministry of Education of China (grant No. IRT1148), a project funded by the priority academic program development of Jiangsu higher education institutions (PAPD, YX03001), the Qing Lan project of Jiangsu province, the Singapore Ministry of Education (MOE2010-T2-1-083), Natural Science Foundation of Jiangsu Province of China (BM2012010) and the National Basic Research Program of China (973 Program) (2012CB933301, 2012CB723402, 2015CB932200 and 2014CB648300).

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  1. Zhongfu An and Chao Zheng: These authors contributed equally to this work.

Authors and Affiliations

  1. Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

    Zhongfu An, Chao Zheng, Ye Tao, Runfeng Chen, Ting Chen, Zhixiang Wang, Huanhuan Li & Wei Huang

  2. Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, China

    Zhongfu An, Runfeng Chen, Huifang Shi & Wei Huang

  3. Department of Chemistry, National University of Singapore, Singapore 117543, Singapore

    Renren Deng & Xiaogang Liu

  4. Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 117602, Singapore

    Xiaogang Liu

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  1. Zhongfu An
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Contributions

Z.A., C.Z., Y.T., R.C., X.L. and W.H. conceived the experiments. R.C., X.L. and W.H. prepared the paper. Z.A., C.Z., Y.T. and H.S. were primarily responsible for the experiments. R.D., Z.W. and H.L. performed the lifetime measurements. T.C. contributed to TD-DFT calculations. All authors contributed to the data analyses.

Corresponding authors

Correspondence to Runfeng Chen, Xiaogang Liu or Wei Huang.

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An, Z., Zheng, C., Tao, Y. et al. Stabilizing triplet excited states for ultralong organic phosphorescence. Nature Mater 14, 685–690 (2015). https://doi.org/10.1038/nmat4259

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